php - Fatal error to Call to a member function fetch_assoc() - why is fetch_assoc() is not working?

itemprop="text">

Here is the error DbOperations. php
codes:

public function
            getUserByUserid($user_id){
 $stmt = $this->con->prepare("SELECT * FROM
            mydb.User WHERE user_id = ?" );
 $stmt->bind_param("s",
            $user_id);
 return
            $stmt->get_result()->fetch_assoc();
}

In
another userLogin.php, i use the getUserByUserid($user_id)
here:

if($db->userLogin($_POST['user_id'],
            $_POST['password'])){
 $user =
            $db->getUserByUserid($_POST['user_id']);
 $response['error'] =
            false;
 $response['user_id'] = $user['user_id'];
 $response['name']
            = $user['name'];
 $response['contact_no'] = $user['contact_no'];

            $response['email'] = $user['email'];
 $response['role'] =
            $user['role'];

And
this is the error
message:

Fatal
            error: Call to a member function fetch_assoc() on a non-object
            in
C:\xampp\htdocs\Android\includes\DbOperations.php on
            line
41

Line
41 is : return
$stmt->get_result()->fetch_assoc();

Not
sure what is the fetch_assoc() issue and i am a beginner...Thank you for
helping:)

Answer

You must execute
a query before trying to get results. Usually it is done with href="http://php.net/manual/en/mysqli-stmt.execute.php" rel="nofollow
noreferrer">execute:

public
            function getUserByUserid($user_id){
 $stmt = $this->con->prepare("SELECT
            * FROM mydb.User WHERE user_id = ?" );
 $stmt->bind_param("s",
            $user_id);
 // Executing a query

            $stmt->execute();


 return
            $stmt->get_result()->fetch_assoc();
}

Going
further you can check if your execution completed succesfully
(get_result() returns not false in
this case) and in case of error - somehow get error message with
mysqli_errno() for example. More info (as
usual) in a href="http://php.net/manual/ru/mysqli-stmt.get-result.php" rel="nofollow
noreferrer">manual.